Commercial and residential pools and spas, for example, swimming pools, hydrotherapy spas and jetted tubs, typically include a filtration system, a circulation pump and oftentimes a heater for heating a body of water within the pool or spa. Without an effective water treatment system, bacteria and algae will grow in the body of water, presenting a health hazard to users of the pool or spa.
It is known that ozone can be an effective oxidizing and sanitizing agent for treating water in a spa or pool. Ozone gas is sometimes mixed with water to form a sanitizing treatment stream that is introduced into the body of water being sanitized. Unfortunately, conventional ozone water mixing systems are not ideal for use in forming an ozonated water treatment stream that is suitable for use with conventional pools or spas, particularly with respect to small scale applications, for example, residential pools and spas.
Conventional water sanitizing systems using ozone do not effectively mix ozone gas with the water being sanitized. Ozone which is not properly mixed with water in an ozonated water treatment stream escapes into the atmosphere. If the pool or spa is located indoors, undissolved ozone gas can build up to undesirable, unhealthful levels and adversely impact air quality. In addition, the unmixed ozone gas that escapes into the atmosphere is wasted, thereby requiring higher quantities of ozone to be introduced into a mixing stream than would otherwise be necessary if the mixing was more effective.
Spa and pool purification systems utilizing ozone have traditionally been limited in their ability to apply sanitizing concentrations of ozone due to regulatory restrictions on the amount of ozone gas that can be discharged at the pool or spa surface. Importantly, the efficiency of ozone as a sanitizing agent is limited without proper and sufficient mixing of the gas with water.
Therefore, it can be appreciated that ozonation of water for purposes of oxidation and sanitation requires efficient transfer of ozone gas, in the dissolved state, into water in the ozonated water treatment stream. Inefficient dissolution, or mass transfer, of ozone into the water results in wasted, undissolved ozone gas being released from the surface of the water. Some conventional systems exist that are designed for very efficient mass transfer (e.g., about 99% or higher) but may still produce off-gassing of high concentrations of ozone.
For these and other reasons, large scale commercial spa and pool systems using ozone for purification conventionally utilize separate, individual components to provide the necessary functions of (1) injection of ozone gas into water, (2) mixing of the ozonated water, and (3) separation and venting of undissolved gas, including ozone gas, from the ozonated water stream. These separate components are relatively bulky, complicated to interconnect, and take up significant amounts of space, which limits their practical and cost effective use to large scale commercial applications, not to consumer or residential applications. Although combination ozone injectors and mixing chambers are commercially available, they are typically too large, expensive and/or technically complicated for use on residential size pools and spas. For example, one such combination system commercially available relies upon large, serpentine pipes to provide the mixing function.
A conventional ozone/water mixing system for a hydrotherapy spa is disclosed in Leaverton et al., U.S. Pat. No. 5,665,228, the entire disclosure of which is incorporated herein by this specific reference.
Conventional ozone water treatment systems have used common water/air valves such as steam traps to collect and vent undissolved gases. These valves are not generally built of ozone compatible materials and tend to pass a fair amount of water along with the vented gases. This leads to problems with reliability and function of the degas/destruct system which is essential to the safe operation of the ozone system.
Most commercial systems utilize a degassing valve to capture and vent the undissolved gases and a destruct unit to destroy the ozone before venting the air stream. Destruct units are constructed in various ways that will be known to those of skill in the art and involved in the industry.
One common method of destroying ozone off-gas in low to medium range concentrations (less than about a few hundred ppm or up to about a few thousand ppm) is by passing the off-gas through a catalyst bed. These catalyst beds are most effective when ozone is allowed to come in direct contact with the catalyst material itself, and only if the material remains sufficiently dry. Commercial heaters are therefore sometimes employed to prevent condensation and moisture intrusion into the catalyst bed.
There remains a need for more cost effective destruct apparatus and methods for preventing water intrusion from the degas stream into the catalyst bed.
The present invention addresses these issues in a cost effective manner designed specifically for use with ozone water treatment systems but with other applications as well.